Fluid pump

ABSTRACT

A fluid pump includes an inlet for introducing fluid into the fluid pump and an outlet for discharging fluid from the fluid pump. The fluid pump also includes a motor having a shaft that rotates about an axis. An impeller includes an array of blades radially surrounding the axis. The impeller is rotatable by the shaft of the motor such that rotation of the impeller pumps fluid from the inlet to the outlet. A vibration isolation member applies a force on the shaft such that the force has a component that is perpendicular to the axis.

TECHNICAL FIELD OF INVENTION

The present invention relates to a fluid pump; more particularly to a fuel pump; even more particularly to a fuel pump which includes a vibration isolation member for damping vibrations from rotating members.

BACKGROUND OF INVENTION

Fluid pumps, and more particularly fuel pumps for pumping fuel, for example, from a fuel tank of a motor vehicle to an internal combustion engine of the motor vehicle, are known. U.S. Pat. No. 5,338,151 shows one type of fuel pump which includes an impeller. An inlet plate is disposed adjacent to one face of the impeller and an outlet plate is disposed adjacent to the face of the impeller that is opposite the inlet plate. An electric motor of the fuel pump includes a shaft which is coupled to the impeller. One end of the shaft is supported radially by a bushing formed integrally with the outlet plate. Rotation of the impeller by an electric motor pumps fuel from an inlet of the fuel pump, to an outlet of the fuel pump. Manufacturing variations in the inlet plate, outlet plate, impeller, shaft, and bushing may lead to vibrations that can be transmitted through components of the fuel pump. These vibrations may result in an audible noise that is not desirable.

What is needed is a fuel pump which minimizes or eliminates one or more of the shortcomings as set forth above.

SUMMARY OF THE INVENTION

Briefly described, a fluid pump includes an inlet for introducing fluid into the fluid pump and an outlet for discharging fluid from the fluid pump. The fluid pump also includes a motor having a shaft that rotates about an axis. An impeller includes an array of blades radially surrounding the axis. The impeller is rotatable by the shaft of the motor such that rotation of the impeller pumps fluid from the inlet to the outlet. A vibration isolation member applies a force on the shaft such that the force has a component that is perpendicular to the axis.

BRIEF DESCRIPTION OF DRAWINGS

This invention will be further described with reference to the accompanying drawings in which:

FIG. 1 is an axial cross-sectional view of a fuel pump in accordance with the present invention;

FIG. 2 is an axial view of an inlet plate of the fuel pump of FIG. 1;

FIG. 3 is an axial view of an outlet plate of the fuel pump of FIG. 1;

FIG. 4 is an isometric view of an impeller of the fuel pump of FIG. 1;

FIG. 5 is a cross-sectional view of the outlet plate of FIG. 3;

FIG. 6 is a cross-sectional view of a second embodiment of the outlet plate of FIG. 3; and

FIG. 7 is a cross-sectional view of a second embodiment of the inlet plate of FIG. 2.

DETAILED DESCRIPTION OF INVENTION

Reference will be made to FIG. 1 which is an axial cross-sectional view of a fluid pump illustrated as fuel pump 10 for pumping liquid fuel, for example gasoline or diesel fuel, from a fuel tank (not shown) to an internal combustion engine (not shown). While the fluid pump is illustrated as fuel pump 10, it should be understood that the invention is not to be limited to a fuel pump, but could also be applied to fluid pumps for pumping fluids other than fuel. Fuel pump 10 generally includes a pump section 12 at one end, a motor section 14 adjacent to pump section 12, and an outlet section 16 adjacent to motor section 14 at the end of fuel pump 10 opposite pump section 12. A housing 18 of fuel pump 10 retains pump section 12, motor section 14 and outlet section 16 together. Fuel enters fuel pump 10 at pump section 12, a portion of which is rotated by motor section 14 as will be described in more detail later, and is pumped past motor section 14 to outlet section 16 where the fuel exits fuel pump 10.

Motor section 14 includes electric motor 20 which is disposed within housing 18. Electric motor 20 includes a shaft 22 extending therefrom into pump section 12. Shaft 22 rotates about axis 24 when an electric current is applied to electric motor 20. One end of shaft 22 is radially supported within outlet section 16 while the other end of shaft 22 is radially supported within pump section 12 as will be described in more detail later. Electric motors and their operation are well known, consequently, electric motor 20 will not be discussed further herein.

With continued reference to FIG. 1 and with additional reference to FIGS. 2-5, pump section 12 includes an inlet plate 26, an impeller 28, an outlet plate 30, and a spacer ring 32. Inlet plate 26 is disposed at the end of pump section 12 that is distal from motor section 14 while outlet plate 30 is disposed at the end of pump section 12 that is proximal to motor section 14. Both inlet plate 26 and outlet plate 30 are fixed relative to housing 18 to prevent relative movement between inlet plate 26 and outlet plate 30 with respect to housing 18. Impeller 28 is disposed axially between inlet plate 26 and outlet plate 30 and is fixed to shaft 22 such that impeller 28 rotates with shaft 22 in a one-to-one relationship. Spacer ring 32 is also disposed axially between inlet plate 26 and outlet plate 30, however, spacer ring 32 is fixed relative to housing 18 to prevent relative movement between housing 18 and spacer ring 32. Spacer ring 32 is dimensioned to be slightly thicker, i.e. the dimension of spacer ring 32 in the direction of axis 24 is slightly greater than the dimension of impeller 28 in the direction of axis 24. In this way, inlet plate 26, outlet plate 30, and spacer ring 32 are fixed within housing 18, for example by crimping the end of housing 18 proximal to outlet plate 30. Axial forces created by the crimping process will be carried by spacer ring 32, thereby preventing impeller 28 from being clamped tightly between inlet plate 26 and outlet plate 30 which would prevent impeller 28 from rotating freely. Spacer ring 32 is also dimensioned to have an inside diameter that is larger than the outside diameter of impeller 28 to allow impeller 28 to rotate freely within spacer ring 32 and axially between inlet plate 26 and outlet plate 30.

Inlet plate 26 is generally planer and circular in shape, i.e. disk shaped, and includes an inlet 34 that extends through inlet plate 26 in the same direction as axis 24. Inlet 34 is a passage which introduces fuel into fuel pump 10. Inlet plate 26 also includes an inlet plate flow channel 36 formed in the face of inlet plate 26 that faces toward impeller 28. Inlet plate 26 also includes an inlet plate aperture 38 extending into inlet plate 26 from the face of inlet plate 26 that is proximal to impeller 28. A portion of shaft 22 may extend into inlet plate aperture 38 such that shaft 22 is able to rotate freely within inlet plate aperture 38.

Outlet plate 30 is generally planer and circular in shape, i.e. disk shaped, and includes an outlet plate outlet passage 40 that extends through outlet plate 30 in the same direction as axis 24. Outlet plate outlet passage 40 is in fluid communication with outlet section 16 as will be describe in more detail later. Outlet plate 30 also includes an outlet plate flow channel 42 formed in the face of outlet plate 30 that faces toward impeller 28. Outlet plate 30 also includes an outlet plate aperture 44 extending through outlet plate 30 such that shaft 22 extends through outlet plate aperture 44 such that shaft 22 is able to rotate freely within outlet plate aperture 44.

Impeller 28 includes a plurality of blades 46 arranged in a polar array radially surrounding and centered about axis 24 such that blades 46 are aligned with inlet plate flow channel 36 and outlet plate flow channel 42. Blades 46 are each separated from each other by a blade chamber 48 that passes through impeller 28 in the general direction of axis 24. Impeller 28 may be made, for example only, by a plastic injection molding process in which the preceding features of impeller 28 are integrally molded as a single piece of plastic.

Outlet section 16 includes an end cap 50 having outlet 52 for discharging fuel from fuel pump 10. Outlet 52 may be connected to, for example only, a conduit (not shown) for supplying fuel to an internal combustion engine (not shown). Outlet 52 is in fluid communication with outlet plate outlet passage 40 of outlet plate 30 for receiving fuel that has been pumped by pump section 12. End cap 50 also includes an end cap shaft support 54 which radially supports one end of shaft 22.

In operation, inlet 34 is exposed to a volume of fuel (not shown) which is to be pumped to, for example only, an internal combustion engine (not shown). An electric current is supplied to electric motor 20 in order to rotate shaft 22 and impeller 28. As impeller 28 rotates, fuel is drawn through inlet 34 into inlet plate flow channel 36. Blade chambers 48 allow fuel from inlet plate flow channel 36 to flow to outlet plate flow channel 42. Impeller 28 subsequently discharges the fuel through outlet plate outlet passage 40 and consequently through outlet 52.

Reference will now be made to FIGS. 1 and 5. A plurality of resilient vibration isolation members 56 are provided in order to radially support the end of shaft 22 that extends into pump section 12. Vibration isolation members 56 are arranged to dampen vibrations that may result, for non-limiting example only, by rotational imbalance of shaft 22 and impeller 28. While three vibration isolation members 56 are shown, it should be understood that more or fewer vibration isolation members 56 may be included. Vibration isolation members 56 may be equally spaced relative to each other about axis 24 as shown.

Each vibration isolation member 56 may be disposed in a respective recess, illustrated as vibration isolation member bores 58, formed in outlet plate 30. Vibration isolation member bores 58 may extend radially outward through outlet plate 30 from outlet plate aperture 44 to an outer perimeter 60 of outlet plate 30.

Vibration isolation member 56 may include a damping member, illustrated as a spring 62, which is resilient and compliant. Spring 62 may be selected to have a spring rate or spring constant that facilitates isolation of the frequencies generated due to the rotational imbalance of shaft 22 and impeller 28. Vibration isolation member 56 may also include a shaft follower member, illustrated as a ball 64, which rides against shaft 22. Vibration isolation member 56 may also include a damping member stop 66 which is grounded to outlet plate 30 within vibration isolation member bore 58 in order to provide a surface for spring 62 to react against. Damping member stop 66 may be press fit within vibration isolation member bore 58. Alternatively, damping member stop 66 may include external threads which threadably engage internal threads located within vibration isolation member bore 58 in order to secure damping member stop 66 within vibration isolation member bore 58. Also alternatively, damping member stop 66 may be welded, heat staked, or secured by other suitable means. Damping member stop 66 may be positioned sufficiently far into vibration isolation member bore 58, either by pressing or threading, in order to compress spring 62 sufficiently to achieve a desired force to be applied on shaft 22 by ball 64. The force applied on shaft 22 by ball 64 includes at least a component that is perpendicular to axis 24. In this way shaft 22 is supported radially with vibration isolation members 56 such that when shaft 22 and impeller 28 are rotated, rotational imbalance of shaft 22 and impeller 28 is dampened by vibration isolation members 56 which may reduce or eliminate vibrations from shaft 22 and impeller 28 from being transmitted to other components of fuel pump 10 which could otherwise result in objectionable noise.

In order to compensate for tolerances that may cause shaft 22 and impeller 28 to move in the direction of axis 24 in use, an axial compensation member 67 may be included. Axial compensation member 67 may be resilient and compliant and may be positioned within inlet plate aperture 38 to provide a biasing force to shaft 22 in the direction of axis 24 toward outlet section 16.

Reference will now be made to FIG. 6 which illustrates an alternative embodiment. FIG. 6 shows outlet plate 30′ which may be used as an alternative to outlet plate 30. Unlike outlet plate 30 which includes three vibration isolation members 56, outlet plate 30′ includes one vibration isolation member 56′. Vibration isolation member 56′ is arranged to dampen vibrations that may result, for non-limiting example only, by rotational imbalance of shaft 22 and impeller 28.

While outlet plate aperture 44 of outlet plate 30 may be substantially circular as shown, outlet plate aperture 44′ of outlet plate 30′ may preferably be non-circular in order to positively cradle shaft 22 between two sides of outlet plate aperture 44′, thereby forming two lines of contact 68 between shaft 22 and outlet plate aperture 44′. As shown in FIG. 6, outlet plate aperture 44′ is illustrated as a Reuleaux triangle, however, outlet plate aperture 44′ may take the form of other shapes that allow shaft 22 to be positively cradled, thereby forming two lines of contact 68 between shaft 22 and outlet plate aperture 44′.

Vibration isolation member 56′ may include a damping member, illustrated as a spring 62′, which is resilient and compliant. Spring 62′ may be selected to have a spring rate or spring constant that facilitates isolation of the frequencies generated due to the rotational imbalance of shaft 22 and impeller 28. Vibration isolation member 56′ may also include a shaft follower member, illustrated as a follower pad 70, which rides against shaft 22 and is contoured to match the outer surface of shaft 22. Vibration isolation member 56′ may also include a damping member stop 66′ which is grounded to outlet plate 30 within vibration isolation member bore 58′ in order to provide a surface for spring 62′ to react against. Damping member stop 66′ may be press fit within vibration isolation member bore 58. Alternatively, damping member stop 66 may include external threads which threadably engage internal threads located within vibration isolation member bore 58′ in order to secure damping member stop 66′ within vibration isolation member bore 58′. Damping member stop 66′ may be positioned sufficiently far into vibration isolation member bore 58′, either by pressing or threading, in order to compress spring 62′ sufficiently to achieve a desired force to be applied on shaft 22 by follower pad 70. The force applied on shaft 22 by follower pad 70 includes at least a component that is perpendicular to axis 24. Preferably, the force applied on shaft 22 by follower pad 70 is in line with both axis 24 and an apex 72 of outlet plate aperture 44′ as illustrated by arrow F. In this way shaft 22 is supported radially with vibration isolation member 56′ and outlet plate aperture 44′ such that when shaft 22 and impeller 28 are rotated, rotational imbalance of shaft 22 and impeller 28 is dampened by vibration isolation member 56′ which may reduce or eliminate vibrations from shaft 22 and impeller 28 from being transmitted to other components of fuel pump 10 which could otherwise result in objectionable noise.

Reference will now be made to FIG. 7 which illustrates an alternative embodiment. While FIGS. 1, 5, and 6 apply vibration isolation members 56, 56′ to outlet plates 30, 30′ respectively, vibration isolation members 56, 56′ may instead by applied to inlet plate 26′ which may be used as an alternative to inlet plate 26. As illustrated, inlet plate 26′ may include vibration isolation members 56 which are arranged within inlet plate 26′ in the same way that vibration isolation members 56 were previously described in relation to outlet plate 30.

While the damping members of vibration isolation members 56, 56′ have been illustrated as springs 62, 62′ respectively, it should now be understood that the damping members may take other forms, for example only, an elastomer block that provides the appropriate compliant and resilient properties to dampen vibrations due to rotational imbalance of shaft 22 and impeller 28.

While the shaft follower members have been illustrated as balls 64 and follower pad 70, it should be understood that other geometries may be substituted while not deviating from the spirit of the invention.

While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited. 

We claim:
 1. A fluid pump comprising: an inlet for introducing fluid into said fluid pump; an outlet for discharging fluid from said fluid pump; a motor having a shaft that rotates about an axis; an impeller having an array of blades radially surrounding said axis, said impeller being rotatable by said shaft of said motor wherein rotation of said impeller pumps fluid from said inlet to said outlet; and a vibration isolation member applying a force on said shaft, said force having a component that is perpendicular to said axis.
 2. A fluid pump as in claim 1 further comprising a plate disposed axially adjacent to said impeller such that said impeller rotates relative to said plate, wherein said vibration isolation member is disposed within a recess of said plate.
 3. A fluid pump as in claim 2 wherein said plate is an outlet plate having an outlet passage in fluid communication with said outlet and an outlet plate flow channel aligned with said array of blades.
 4. A fluid pump as in claim 2 wherein said recess is a bore extending radially into said plate.
 5. A fluid pump as in claim 4 wherein said vibration isolation member includes a damping member that is resilient and compliant.
 6. A fluid pump as in claim 5 wherein said damping member is a spring.
 7. A fluid pump as in claim 5 wherein said vibration isolation member includes a damping member stop for grounding said vibration isolation member to said plate.
 8. A fluid pump as in claim 7 wherein said damping member stop is fixed within said bore to compress said damping member between said shaft and said damping member stop.
 9. A fluid pump as in claim 7 wherein said damping member includes a shaft follower member disposed between said shaft and said damping member.
 10. A fluid pump as in claim 9 wherein said shaft follower member is a ball.
 11. A fluid pump as in claim 9 wherein said shaft follower member is a follower pad contoured to match the outer surface of said shaft.
 12. A fluid pump as in claim 4 wherein said plate includes an aperture and wherein said shaft extends into said aperture.
 13. A fluid pump as in claim 12 wherein said bore extends radially outward from said aperture.
 14. A fluid pump as in claim 12 wherein said aperture is non-circular.
 15. A fluid pump as in claim 14 wherein said vibration isolation member biases said shaft into contact with said aperture.
 16. A fluid pump as in claim 15 wherein said shaft forms two lines of contact with said aperture.
 17. A fluid pump as in claim 16 wherein said aperture is a Reuleaux triangle.
 18. A fluid pump as in claim 4 wherein said vibration isolation member is one of a plurality of vibration isolation members.
 19. A fluid pump as in claim 18 wherein said plurality of vibration isolation members are spaced evenly around said axis.
 20. A fluid pump comprising: an inlet for introducing fluid into said fluid pump; an outlet for discharging fluid from said fluid pump; a motor having a shaft that rotates about an axis, wherein rotation of said impeller pumps fluid from said inlet to said outlet; and a vibration isolation member applying a force on said shaft, said force having a component that is perpendicular to said axis. 